I have CAI,LT headers, cattted X pipe, FRPP GTA's and a custom tune. The LT headers were the last thing that I did and it got much louder than I'd like. Would switching back to the stock mufflers hurt performance? If so, how much?
Someone even told me it may increase the back pressure and increase the low end torque (but hurt high end HP)? Is this true?

 

It it will be fine. The stock mufflers are pretty good with regard to flow.

 

Wont hurt a thing, you may even gain 1 or 2 pony's

 

nope

 

If ya decide to go stock and wanna sell the GTA's, let me know.

 

The stock exhaust set-up is accually very good. You may loose a little bit of sound, but the performance should be close.